Field of the Invention
The present invention relates to a method for preparing an isobenzofuran-1(3H)-one based compound, especially a method for preparing (Z)-3-butylidene isobenzofuran-1(3H)-one, i.e., (Z)-n-butylidenephthalide.
Descriptions of the Related Art
3-butylidene isobenzofuran-1(3H)-one (molecular formula: C12H12O2; molecular weight: 188.22) is a mono-terpene compound useful for treating various tumors, such as glioblastoma multiforme and mammary cancer (see Tsai et al., Clin. Cancer Res. 2005, 11(9): 3475-3484 and Tsai et al., J Neurochem. 2006, 99(4): 1251-62). In the past, 3-butylidene isobenzofuran-1(3H)-one has been isolated from the extracts of Angelica sinensis. However, the isolated product is a mixture comprising both (Z)-3-butylidene isobenzofuran-1(3H)-one and (E)-3-butylidene isobenzofuran-1(3H)-one component, and it is difficult to further separate (Z)-3-butylidene isobenzofuran-1(3H)-one from (E)-3-butylidene isobenzofuran-1(3H)-one component. Therefore, all commercially available 3-butylidene isobenzofuran-1(3H)-one are a mixture of (Z)-3-butylidene isobenzofuran-1(3H)-one and (E)-3-butylidene isobenzofuran-1(3H)-one. If such mixture is used in the pharmaceutical industry, it would be difficult to control the impurities.
In view of the above, the present invention provides a synthetic method for preparing an isobenzofuran-1(3H)-one based compound, especially for preparing (Z)-3-butylidene isobenzofuran-1(3H)-one.